Studies of Mental “Noise”

Successive tests of subjects' performance in reaction time tasks were treated as time series and submitted to spectrum analysis. Rather than revealing the white noise expected by the view that variability is due to random error (equivalent power across frequency), the power spectra revealed colored noise. The slopes of the power spectra did not vary much for tasks differing in memory requirements. Spectrum analysis of time series from the logistic map also showed colored noise in regions on the edge of chaos, showing that the presence of colored noise in cognitive data need not oblige a theoretical account based on a complex, high-dimensional, system.     

An efficient quantitative ultrasonic elastography based on variational h-refinement

Quantitative elastography is a method to visualise a stiffness distribution. It is motivated by the observation that changes in mechanical properties of soft tissue mostly include important diagnostic information. With an ultrasound–elastography system, the displacement field can be calculated from the pre– and post–deformation image. Using the assumption that the material is elastic, isotropic and nearly incompressible, the distribution of shear modulus is determined by solving an inverse problem. While common approaches use a constant mesh, a variational h–refinement is in the focus of this work. In doing so, the efficiency and accuracy of the determination can be increased. The presented results are generated by using numerical simulations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fatigue life investigation using non-destructive testing methods

Experimental investigations of the fatigue life prediction of two different specimen forms made from steel 42CrMo4 are described. The fatigue load is defined as a cyclic loading with constant and non constant amplitudes in tension range and with different stress ratios. This loading range leads to a high cyclic fatigue behaviour of both specimens. During the test, the growth of the fatigue crack is monitored using two different non-destructive methods, namely acoustic emission and the electric resistance. The acoustic emission is used for detecting sound waves as a result of dissipation of elastic energy during microcracks and cracks growth, as well as for the detection of the place of crack initiation. The electric resistance is used for the monitoring and quantitative investigation of the crack growth. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermomechanical behavior of pseudoelastic NiTi shape memory alloys

The thermomechanical behavior of polycrystalline Ni-rich pseudoelastic NiTi shape memory alloys is analyzed. Special focus is on regions within the stress strain diagram which are regarded as linear elastic in common phenomenological material models, i.e. the region between zero stress and the beginning of the pseudoelastic plateau as well as the region within the hysteresis. In both cases, severe temperature changes can be observed. A possible explanation for this effect is twofold: On the one hand, it might be explained by the presence of an R-phase transformation. On the other hand, unstructured martensite of the B19' phase may form. However, the assumption of a purely thermo-elastic material behavior in those regions does not seem to hold true in general. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Untersuchung von Schokolade, Marzipan, Zucker, Fruchtsaft, Marmelade, Gelee usw

Ohne Zusammenfassung     

Zuckerbestimmungen

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Einen aichungsf?higen Polarisationsapparat

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